Testing current or voltage

I have an interesting electrical scenario. I was looking at the specs
for a flying probe tester and noticed that it tests for shorts or opens
using voltage or current. The listed specs for the tester are
adjustable 25 to 250v and 30 to 300mA. I need to figure out how I can
generate these different voltage/currents and to check for a pass/fail.
What kind of circuit can vary these voltage and currents and check for
that type of signal. It's such a wide range and changing the circuit to
test all the different combinations of voltage and current evades my
thinking. I'm not familiar with this type of circuit at all so any
suggestions would be great. Thank you!